Heat process for crankshafts



Feb. 21, 1967 CARY 3,305,409

HEAT PROCESS FOR CRANKSHAFTS Original Filed Dec. 26, 1962 3 Sheets-Sheet 1 Feb. 21, 1967 P. E. CARY HEAT PROCESS FOR CRANKSHAFTS 3 Sheets-Sheet 2 I Original Filed Dec.

Feb. EL 1967 P. E. CARY 3365,40

HEAT PROCESS FOR CRANKSHAFTS Original Filed Dec. 26, 1962 3 Sheets-Sheet 5 gyfl United States Patent ()fiice 3,305,409 HEAT PROCESS FOR CRANKSHAFTS Philip E. (Iary, Juliet, 1113., assignor to International Harvester Company, Chicago, 11]., a corporation of Delaware Uriginal application Dec. 26, 1962, Ser. No. 247,168, new Patent No. 3,240,480, dated Mar. 15, 1966. Divided and this application Dec. 26, 1965, Ser. No. 515,046 '7 Claims. (Cl. 148-446) This invention relates to a heat treating process particularly adapted for the hardening of cranksha fts. More specifically, the invention relates to an improved heat treating process for hardening the bearing and fillets of crankshafts and the like. The present patent application is a division of applicants patent application Serial No. 247,168 filed December 26, 1962 entitled, Heat Treating Apparatus for Crankshafts, which issued on March 15, 1966 and is now U.S. Patent No. 3,240,480.

Hereto fore, apparatuses utilized for the hardening of the bearings and fillets of crankshafts employing induction heating elements generally included a quench coil integral with the inductor coil whereby the heated bearing surface was quenched by quench liquid flowing from quench openings of the integral quench coil or, alternatively, the heated bearing surface was quenched by providing the heat treating apparatus with means for lowering or immersing the crankshaft into a quench bath within a quench tank immediately after the bearing surface was inductively heated. Certain apparatuses of the latter type also included means for continually circulating the quench fluid in the quench tank during operation of the apparatus. Such circulation means oftentimes included nozzles as mentioned in the G. Seulin et al. Patent No. 2,787,566 issued April 2, 1957.

Previous apparatuses of the type mentioned above have been satisfactory to a degree in the hardening of hearing surfaces. where limited fillet hardening is accomplished. Thus several of the fillet areas of a crankshaft may have been satisfactorily hardened, but no one in the crankshaft hardening field heretofore has successfully hardened all of the fillet areas of a crankshaft without distorting or cracking the chankshaft to a degree where it is unusable for its intended purpose. The hardening of all fillet areas of a crankshaft is becoming increasingly important in view of the increasing horsepower requirements of modern day internal combustion engines. With an increase in horsepower, linear bending movements about the axis of the crankshaft also increase and such amplified linear bending movements oftentimes causes a rapid breakage of the crankshaft particularly in the fillet areas. Thus, a process suitable for satisfactorily hardening all fillet areas of a crankshaft without detrimental distortion or cracking has been one of the compelling needs of the industry. It is therefore one of the primary objectives of the present invention to provide an improved process which satisfies this need.

Another prime object is to provide animproved process for hardening all fillet areas of bearings of a crankshaft without appreciable distortion or cracking of the crankshaft.

It is another object of this invention to provide an improved induction heating process for hardening the bearings and fillets of crankshafts on a mass production basis.

Still another object is to provide an improved process for heat treating crankshafts wherein each bearing surface including t-he fillet areas adjacent thereto of the crankshaft is subjected to high velocity, concentrated jetlike quench streams immediately after being heated to a particular temperature.

A still further object is to provide an improved heat 3,3fi5g4h9 Patented Feb. 21, 1967 treating process employing a quench step wherein a particular bearing surface is subjected to the impinging action of a plurality of pressurized jet-like streams of quench fluid simultaneously with the inductive heating of a particular bearing surface of another crankshaft.

The foregoing and other objects and desirable features inherent in and encompassed by the invention, together with many of the purposes and uses thereof, will become readily apparent from a reading of the following description in conjunction with the annexed drawings, in which:

FIGURE 1 is a side elevational view, partially in section, of an induction hardening apparatus which can be employed to practice the invention;

FIGURE 2 is a partial plan view taken substantially along line 22 of FIGURE 1;

FIGURE 3 is a front elevational view of the apparatus shown in FIGURE 1, certain portions of the quench tank are broken away to better illustrate the invention;

FIGURE 4 is a vertical sectional view taken substan tially along the line 44 of FIGURE 4;

FIGURE 5 is a cross-sectional view taken substantially I along line 5 S of FIGURE 4;

FIGURE 6 is an enlarged sectional view similar to FIGURE 5, the manner in which a quench block is atv taohed to the quench tank wall;

' and On occasion they have been satisfactory FIGURE 11 is a detail schematic view illustrating the flow characteristics of the high impact velocity jet-like streams in relation to a heated crankshaft bearing which is being quenched.

Referring to the drawings in detail wherein like reference characters represent like elements throughout the various views, a crankshaft induction heating and quenching apparatus capable of being employed to practice the process of the present invention is designated generally by reference character 10. The apparatus 10 includes a quench tank 11, the walls of which define a quench tank chamber 12. A workpiece holder or crankshaft carrier 13 is disposed within the quench chamber 12 and comprises a rotatable casing 14 having supported thereon four work rotating members or plates 15. The casing 14 also includes a rectangular support block 16 which is rotatable with the casing 14 and extends lengthwise within the quench tank 11. The support block 16 is suitably supported by means of bearings (not shown) at its righthand end as viewed in FIGURE 2. The casing 14 contains suitable planetary gear means generally designated at 17. Upon rotation of a shaft 18, the casing 14 and support block 16 rotate and by means of the gear means 17, the work rotating members or face plates 15 are also rotated in the directions of the arrows shown in FIGURE 1. A suitable collar unit 19 is supported on the quench tank 11 for imparting rotational movement to the shaft 18 and the casing 14 in order to rotate the work rotating members 15. Work-pieces in the form of crankshafts are designated generally by numeral 20. Each of the crankshafts 20 has one end rigidly connected on one of the work rotating members 15 and has its other end supported for rotational movement on a lathe-type centering means 21 which centering means 21 are suitably supported on the support block 16 within T-slots 22. It

will be appreciated that by virtue of the connections afforded by the T-slots 22, the centering means 21 are adjustable longitudinally or along the rotational axes of the crankshafts 20 whereby the apparatus is capable of accommodating crank shafts of various lengths. The apparatus 10 is capable of processing four crankshafts 20 as a group and each of the four crankshafts -20 disclosed in FIGURE 1 is supported by the apparatus 10 in the manner pointed out 'hereinbefore. The crankshafts 20 are the type utilized in internal combustion engines and each is provided with a plurality of longitudinally spaced bearings or bearing surfaces which are to be hardened. The bearings for the purpose of this specification will include the known terminology of pin bearings 23 and main bearings 24 (also known as journals). The invention also contemplates the hardening of the fillets of fillet areas 25 at the ends of the cylindrical surface defining the pin and main bearings and, to simplify the description, such fillets and fillet areas 25 will also be included in the term bearing. The fillets 25 are the curved surfaces at the ends of the cylindrical bearing surfaces of the pin and main bearings 23, 24 respectively where each of the bearing surfaces join the masses of metal known as cheeks 26 joining the radially offset pin bearing 23 to the main bearing 24 of the crankshaft 20.

As best shown in FIGURES 1 and 2, 4, 5, 9 and 11, the apparatus 10 includes a plurality of longitudinally spaced quench blocks 27 which are supported within the quench chamber 12. Each quench block 27 includes a rear plate 28, an upper plate 29, a lower wall 30* and side walls 31. The front or inwardly facing wall 32 of each quench block 27 is arcuately shaped as best shown in FIGURE 5 and is provided with a plurality of quench orifices 33 therethrough. The lower wall 30 of each quench block 33 has one end of a conduit 34 connected thereto. Each conduit 34 is in fluid communication with the interior of a respective quench block 27 and is utilized to convey quench fluid to the interior of the quench block 27 with which it is associated.

The quench blocks 27 are supported within the quench tank 11 by means of lower guide straps 35 extending longitudinally and horizontally within the quench tank 11 and by upper guide straps 36 substantially parallel to the lower guide straps 35. The lower guide straps 35 are spaced from the inner surface of one of the tank walls by means of spacer strips 37 and similarly the upper guide straps 36 are spaced from the same inner surface of the tank wall by means of spacer strips 38 which are best shown in FIGURE 6. The guide straps 35 and 36 are secured by means of screws 39 and are adapted to clamp the upper and lower edges of the back or rear plates 28 to securely retain the quench blocks 27 in predetermined longitudinal positions within the quench chamber 12. From the foregoing it will be obvious that by merely loosening the screws 39, the quench blocks 27 may be adjusted horizontally and longitudinally to the positions desired to thus accommodate longer or shorter crankshafts 20 where the bearing lengths are of the same dimension as illustrated in the drawings.

As best shown in FIGURES 1 and 3, the induction heating mechanism is generally designated by reference character 40. The induction mechanism 40 is supported on a suitable platform 41 carried on the quench tank 11. The platform 41 has a pair of horizontally extending track members 42 on which an inductor carrier 43 is positioned. The carrier 43 includes a carriage 44, which by means of bracket structures 45, support four track wheels 46 in a suitable manner. Only two of the four track wheels 46 are illustrated in the drawings but it is to be understood that the track wheels 46 are supported on and engageable with the track members 42 so that the carriage 44 may be moved horizontally and longitudinally along the quench tank 11. The housing, designated generally by reference character 47, has a parallelogram linkage 48 pivotally connected thereto at 49. A second parallelogram linkage 50 is pivotally connected to the linkage 48 and extends downwardly for supporting an inductor unit, designated generally by numeral 51. The inductor unit 51 is provided with a pocket-like inductor portion 52 within which is disposed an inductor coil 53. A transformer is designated generally by reference character 54.

The inductor portion 52 is capable of being lowered over a main bearing 24 or pin bearing 23 in order to position the conductor coil in a heating relation with the bearing. Because of the offset nature of the pin bearings 23 with respect to rotational axis of the crankshaft 20 with which it is associated and since heating of a pin bearing 23 occurs while the crankshaft 20 is rotated about its longitudinal axis, the inductor 52 follows the orbital path taken by the pin bearing 23. The inductor unit 51 may be of a construction similar to that shown in the G. Seulen et al. Patent No. 2,743,345 granted April 25, 1956. Electric conductors or wires 55 suitably connect the transformer 54 to conventional electrical generator components (not shown).

As best shown in FIGURES 1 and 3, an indexing plate 56 is supported by the platform 41 and such indexing plate 56 includes a plurality of horizontally and longitudinally spaced apertures or notches 57 which serve to provide a plurality of horizontally spaced stops. A shaft 58 is suitably supported for rotational movement by means indicated by reference character 59 on the housing 47. A handle 60 is provided to facilitate manual rotation of the shaft 58. The shaft 58 has an arm 61 connected thereto which in turn has a switch-engaging member 62 connected thereto. As best shown in FIGURE 3, the switch-engaging member 62 depends downwardly from the arm 61. Referring to FIGURES 3 and 8 it will be noted that a detent member 63 is provided which has a lower portion conforming to the shape of the notches or apertures 57. The detent member 63 is pivotally connected to an arm 64 which, in turn, is connected to the shaft 58 for rotation therewith. The detent member 63 is pivotally connected as indicated at 65 to the arm 64. A plurality of switch elements 66, one for each notch 57, are disposed below the notches 57 and are suitably connected by means of brackets 67 to the indexing plate 56 as illustrated in FIGURE 1. Each switch element 66 includes a switch actuating plunger 68.

Referring now to the schematic view of FIGURE 7, each switch element 66 is connected to a suitable electrical source by means of wires or conductors 69 and 70. Each switch element 66 is also electrically connected to a solenoid valve 71 by means of conductors or wires 72 and 73. An air line or conduit 74 extends to a suitable source of air under pressure (not shown) and is also connected to a branch conduit 75 which, in turn, opens into the housing of the solenoid valve 71. An air line or conduit 76 leads from the housing of the solenoid valve 71 and a casing 77 of a check valve providing fluid communication between such solenoid valve 71 and the check valve casing 77. The check valve casing 77 is provided with a port 78 which is normally closed by means of a spring-urged ball valve 79. The casing 77 exhausts to the atmosphere through an outlet port 80. The casing 77 is also provided with a suitable bleed orifice 81, the discharge through which may be controlled by means of a needle valve 82. The exhaust port 80 communicates with an air line or conduit 83 which in turn is in fluid communication with an accumulator 84.

An air control valve, designated generally by reference character 85, is connected to an air line or conduit 86 which, in turn, is in fluid communication with the accumulator 84 as well as with a chamber 87. A spool valve 88 is slidingly positionable within the casing of the air control valve and is constructed with lands 89 and 90. Spring means 91 urges the spool valve 88 in the direction toward the conduit 86. An inlet port 92 communicates with the air line 74 and an outlet port 93 is connected to a conduit or air line 94 which, in turn, is connected to a conduit or air line 95 communicating with a diaphragm valve, generally designated by reference character 96. The casing of the air control valve 85 is also provided with a port 97 capable of exhausting air to the atmosphere.

The diaphragm valve 96 comprises a diaphragm 98 and a spring 99. The spring 99 normally holds a movable valve element 190 in a closed position against a valve seat 1191. Upon the application of a predetermined air pressure against the diaphragm 98, the valve element fltltl is moved to its open position to permit quench fluid to be directed under pressure from a conduit 102 to a conduit fitting 193, which fitting 193, in turn, is in fluid communication with a conduit 34 leading to a particular quench block 27 associated therewith. Each of the conduits 192 may receive quench fluid under high pressure from the discharge side of suitable pump means (not shown) which pump may receive quench fluid from tank 11. In this manner quench fluid under relatively high pressure may be directed to the quench blocks 27. Alternatively, the conduits 102 may be connected to a separate source of quench fluid under pressure if desired. A separate switch 66, solenoid valve 71, accumulator 84 and other stated components including a separate quench block 27 are provided for each bearing of the crankshaft to be heat treated and each quench fluid control system is separate in operation.

The operation To commence the operation, the work rotating members or face plates of the crankshaft carrier 13 are loaded with the crankshafts 29, the bearings of Which are to be heat treated. The crankshaft disposed at the top portion of the rotatable casing 14, as viewed in FIGURE 1, is then in the proper position to have either a pin bearing 23 or a main bearing 24 thereof inductively heated. As pointed out hereinbefore the inductor coil 53 is designed in such a manner that the fillets 25 are also heated simultaneously with the cylindrical bearing surfaces of such pin and main bearings 23, 24, respectively, and the surfaces known as fillets are intended to be included in the term bearing throughout the specification and claims as far as the heat treating apparatus and process disclosed are concerned. The inductor carriage 44, being horizontally and longitudinally adjustable upon the track member 42, the inductor unit 51 with the carriage 44 is moved into registry with one of the bearings 23 or 24. The aforesaid movement of the inductor unit 51 may be accomplished by a suitable power drive or manually by the operator moving the inductor carriage 44 on the track members 52. Each of the hearings to be treated of the crankshaft 29, as viewed in FIGURE 1, lies in the same vertical plane perpendicular to the longitudinal axes of the crankshafts 24 as respective bearings of the other crankshafts 26 and each of said bearings of said uppermost crankshaft 20 is in alignment or registration with a respective one of the indexing notches or stops 57. In other words, each of the four crankshafts 20 illustrated in FIGURE 1 has a hearing which is registerable with one of the indexing notches 57. Once the indexing plate 56, which is designed for the particular crankshaft 20 to be processed, is secured in its correct position on the platform 41, the operator moves the inductor unit 51 to one of the notches or apertures 57 corresponding to the particular bearing to be treated after which the shaft 58 is rotated to cause the detent member 53 to enter the desired notch or aperture 57 in alignment with such bearing. In this manner the carriage 44 is locked in position with respect to the platform 41 and is retained against horizontal longitudinal movement. The inductor coil 53 is now in accurate registration with the particular bearing to be heated and the induction coil is thereafter moved downwardly into heating engagement with the particular bearing to be heated and is maintained in such heating engagement during rotation of the crankshaft 20 by its own weight. The entire bearing including the cylindrical surface and the fillet areas thereof is inductively heated during rotation of the crankshaft 20 at the heating station since the inductor coil 53 is being energized simultaneously.

With the detent member 63 in its engaged position as shown in FIGURE 3 the switch-engaging member 62 associated therewith depresses the plunger 68 of the switch 66, adjacent the particular notch 57, closing the switch 56 to electrically operate the solenoid valve 71 associated therewith. The solenoid Valve 71 being actuated causes the air pressure line or conduit 75 to be in fluid communication with the air line or conduit '76. Consequently, air under pressure is admitted into the body of the check valve 77 to displace the ball valve element 79 permitting air pressure to build up Within the accumulator 84. When a predetermined pressure is reached within the accumulator 84, the air pressure in chamber 87 of the air control valve causes the valve 88 to move against the resilient action of the spring means 91. As a result, the land 90 uncovers the ports 92 and 93 whereupon air under pressure flows through the conduits 94 and 95 to the interior of the diaphragm 96 on one side of the diaphragm 98. As a result the diaphragm frame 98 moves to the right, as viewed in FIGURE 7, and the valve 96 is moved to its open position to permit the inflow quenching fluid under pressure to the connection 193- and thence to the conduit 34 of the particular quench block 27 which is in a position to quench the particular hearing which has just been heated at the heating station. It will be appreciated that when the land 90 is in the position wherein the ports 92 and 93 are uncovered the exhaust port 97 is covered. Thus, quench fluid under high pressure is directed, as shown in FIG- URE l, to the proper quench block 27 associated with the particular bearing that was last locally heated.

When the selected bearing, which includes the fillets 25, has been heated to a predetermined temperature the inductor unit 51 is raised and the crankshaft carrier 13 is rotated counterclockwise as viewed in FIGURE 1 so that the last locally heated bearing is completely immersed below the level of the quench fluid in the quench tank 11 and is positioned in the quench tank 11 in close proximity to the quench block 27 receiving pressurized quench fluid. The quench zone occupied by the last locally heated bearing is identified by the letter A and when the bearing is in quench zone A high pressure quench fluid emanating from the adjacent quench block 27 is directed against the cylindrical bearing surface portion and also into the fillet areas adjacent thereto in the form of high pressure, jet-like streams. Simultaneously with the immersion of the crankshaft 20 and the positioning of the heated bearing thereof in the quench zone A, another crankshaft 20 is placed in position for heating and the conductor unit 51 is again lowered into heating relation with respect to a particular bearing thereof. The carriage 43 is maintained locked in this position until the bearings of the other three crankshafts 20 corresponding to the selected bearing of the first crankshaft 20 to be located at the heating station have been heated and quenched. After all of the corresponding bearings of the four crankshafts 20 have been heated and while the last bearing of the four bearings to be heated is being quenched, the operator rotates the arm 61 to lift the detent member 63 from the previously selected aperture or notch 57 whereupon the switch-engaging member 62 is moved upwardly and consequently the switch 66 is deenergized. The solenoid valve 71 associated with such switch 65 now blocks air communication between conduits 75 and 76 whereupon the ball valve 79 closes the opening or port 78. Air from the accumulator 84 now bleeds out the bleed orifice 81 whereupon pressure in the chamber 87 is gradually reduced and the spring means 91 with snap action moves the valve 88 again to the position shown in FIGURE 7 closing ports 92 and 93 and uncovering the exhaust port 97. Since the pressure reduction in the accumulator 94 is gradual, the closing of the diaphragm valve 96 is also gradual and, consequently, quench fluid will continue to flow from the quench block 22 for a predetermined time period to continue to quench the last locally heated bearing disposed within the quench zone A.

The next operational phase involves the unlocking of the inductor carriage 44 from the stationary platform 41 and the repositioning of the inductor carriage 39 along the track member 42 to a new position corresponding to another bearing of the crankshafts 20. When the new position is reached the detent member 63 is again engaged in a respective one of the notches 57 of the indexing plate 56 corresponding to the particular bearing selected. Obviously, the switch-engaging member 62 is caused to actuate or energize the adjacent switch 66 at the new position simultaneously with locking engagement of the detent member 63 with the selected notch 57. It will be appreciated that inasmuch as the air pressure within the accumulator 34 diminishes gradually because of the relatively small size of the bleed orifice 81, the quench fluid continues to flow from the quench block 27 corresponding to the first selected bearings of the crankshafts during the time the inductor unit 51 is being repositioned to dispose the inductor coil 53 in heating relation with a newly selected bearing of the crankshaft 20 disposed above the level of the quench fluid as viewed in FIGURE 1. After all of the selected bearings of all the crankshafts 20 have been heated and quenched, the operator removes the detent member 63 from engagement with the indexing plate 56 and when the air pressure in the diaphragm valve 96 has diminished sufficiently the valve element 100 will be urged to its closed condition by the spring 99 and the flow of quench fluid to the last quench block 27 conditioned to receive quench fluid ceases. As indicated above, each quench block 27 is associated with a separate electric-air system for controlling the flow of quench fluid thereto.

The foregoing description explains some of the operational steps of the process for heat treating crankshafts. As indicated previously, it is important that a separate quench block 27 be designed for each length of bearing of the crankshaft 20 to be processed. Referring to FIG- URE 9, it will be noted that the orifices 33 are oriented so as to direct the quench fluid streams emanating therefrom not only on the straight cylindrical bearing surfaces, but also particularly into the fillet areas 25. The location and angulation of these orifices 33 must be such that the jet streams emanating therefrom impinge directly on the straight cylindrical surfaces of the bearings as well as the adjacent fillet areas and must not be diverted or diminished in speed colliding with each other.

What happens with a conventional quench block clesigned for various length bearings is clearly shown in FIGURE 10 wherein the orifices 104 extend along the flat inwardly facing wall of such conventional quench block 105. In this case the orifices 104 directly in line with the inner edges of the cheeks 26 have streams of quench fluid emanating therefrom which will impinge on the inner edges of the cheeks 26 and thus will be deflected toward the middle area of the cylindrical bearing surface. Consequently the fillet areas will be starved of quench fluid under pressure with the result that the fillet areas 25 will not be properly quenched and heat treated as desired. Thus it is important that the disposition of each orifice 33 is such that the quench fluid emanating therefrom is directed within an area where direct impingement of the stream takes place on the cylindrical bearing surface and fillet areas without any appreciable drop in velocity which undoubtedly occurs when using conventional quench block constructions.

Referring particularly to FIGURE 11, the high velocity jet streams flowing through the orifices 33 are so directed as to completely envelope the heated crankshaft bearing throughout its orbital path. A baffle designated generally by reference letter B is supported on each of the four surfaces of the support block 16 and rotates therewith. Each pair of adjacent bafiles B partially define a high velocity quench zone A in which the heated crankshaft bearing is rotated and serves to insure that substantial impingement of the heated bearing occurs and proper quenching is achieved. The width of the quench block 27 utilized to direct quench fluid under pressure to a particular bearing is chosen so as to be suificiently large enough to direct jet-like streams which completely envelop the bearing in its entire orbital path so that impingement of the jet streams occur on all surfaces of the bearings including the fillet areas 25. The flange portions C at the free ends of the baffles B prevent the jetlike streams of quench fluid from breaking through the surface of the quench bath and spraying on the inductor unit 51 to possibly damage the same. From the foregoing, it will be appreciated that the baffles B, as best shown in FIGURE 11, have upper and lower diagonally spreading portions which in effect throw or deflect the high velocity streams back toward the bearing which is being quenched thereby tending to wipe and further cool the far side of the bearing.

In the process, the crankshaft design is analyzed and by experimental trial and error technique a determination is made as to the required impact velocity of the streams of quench fluid necessary for satisfactorily quenching the bearings of the crankshaft. It is also desirable that the quench blocks be as close to the bearings as possible. Assuming now that a pin bearing 23 is to be quenched, the dimension X in FIGURE 11 may be, for instance, one inch indicating the distance of the outside surface of the pin bearing from the quench block 27. The letters Y may denote two inches each with the dimension Z being the dimension (five inches) from the quench block 27 to the inner side surface of the pin bearing 23 when it reaches a 180 degree position from the position shown in FIG- URE 11. Thus, for instance, then the distance of five inches is the distance of the work from the orifices 33 of the quench block 27.

It has been determined experimentally that in order to achieve proper hardening by efficiently and properly removing the heat from the bearing surface, the impact velocity at five inches must be at least three feet per second in the submerged condition of the crankshaft 20 in the quench fluid. A quench fluid particularly effective is polyvinyl alcohol in a concentration by weight in water of to of 1%. It is then necessary to have the pressure at the orifice of at least seven pounds per square inch which will provide a velocity at the orifices 33 of about 35 feet per second. It is determined, therefore, that for most crankshaft bearings to be satisfactorily quenched, the pressure at the orifices 33 should be within a range of seven pounds per square inch to approximately 50 pounds per square inch.

Impact velocity for submerged work in the above range at a distance of five inches between the work and the orifices 33 require the approximate pressures as shown below.

Submerged 7 p.s.i. at orifice=35 f.s. at orifice=3 f.s. Impact Velocity l7 p.s.i.:Sl f.s. at orifice=5 f.s. Impact Velocity 30 p.s.i. at orifice=67 f.s. at orifice=7 f.s. Impact Velocity 40 p.s.i. at orifice=76 f.s. at orifice=8 f.s. Impact Velocity 5O p.s.i. at orifice= f.s. at orifice=9 f.s. Impact Velocity The above figures with respect to pressures concern the submerged type of quench. When the quench is solely in air then of course the pressure at the orifices would be less in order to achieve the same impact velocities given above. The impact velocities required as above noted are for the plastic quench stated, and would be somewhat different for another quench fluid such as oil for an example. The impact velocities would be at a lower figure when oil is used as the quench fluid to achieve the same quenching action.

With the aforementioned method, the critical areas such as the fillets are precisely hardened so that all of the fillets can be hardened uniformly and Without detrimental distortion to the crankshaft.

The indexing plates are quickly interchanged for different length crankshafts and also the quench blocks can be interchanged and adjusted for different length shafts and lengths of bearings to be heat treated.

The embodiment of the invention chosen for the purposes of illustration and description herein is that preferred for achieving the objects of the invention and for developing the utility thereof in the most desirable manner, due regard being bad to existing factors of economy, simplicity of design and construction and the improvements sought to be effected. It will be appreciated, therefore, that the particular structural and functional aspects emphasized herein are not intended to exclude, but rather to suggest, such other adaptations and modifications of the invention as fall within the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. A process for inductively hardening surface portions of a crankshaft, each of said surface portions including a generally straight cylindrical bearing surface and annular curved fillet surfaces at each end of the bearing surface, comprising the steps of, inductively heating a selected one of said surface portions; and immediately thereafter immersing the entire crankshift bodily into a quench bath of polyvinyl alcohol and water and simultaneously causing said heated surface portion to be impinged With a plurality of pressurized, jet-like streams of polyvinyl alcohol and water quench fluid which streams have velocities at impact of at least three feet per second.

2. A process for inductively hardening surface portions of a crankshaft as set forth in claim 1, wherein the crankshaft is rotated about its own longitudinal axis during the time said heated surface portion is being impinged by said streams of quench fluid.

3. A process for inductively hardening surface portions of a crankshaft as set forth in claim 1, wherein the crankshaft is continually rotated about its own axis during the aforementioned steps.

4. A process for inductively hardening surface portions of a crankshaft, each of said surface portions including a generally straight cylindrical bearing surface and annular curved fillet surfaces at each end of the bearing surface, comprising the steps of, inductively heating a selected one of said surface portions; immediately thereafter immersing the entire crankshaft bodily into a quench bath and simultaneously directing a plurality of jet-like streams of quench fluid under a predetermined pressure toward the inductively heated surface portion; and selecting and maintaining the magnitude of said predetermined pressure to cause said jet-like streams to impinge on said inductively heated surface portion with impact velocities ranging up to substantially nine feet per second.

5. A process for inductively hardening surface portions of a crankshaft as set forth in claim 4, wherein the crankshaft is continually rotated about its own axis during the aforementioned inductive heating and quenching steps.

6. A process for inductively hardening the bearing surface portions of a plurality of crankshafts, each of said bearing surface portions including a generally straight cylindrical bearing surface and annular curved fillet surfaces at each end of the bearing surface, comprising the steps of, positioning one of said crankshafts at a heating station; inductively heating a selected one of the bearing surface portions thereof; immediately thereafter immersing said one crankshaft bodily into a quench bath comprising polyvinyl alcohol and water to position the heated bearing surface portion at a quenching station and simultaneously positioning a second crankshaft at said heating station; inductively heating a selected one of the bearing surface portions of said second crankshaft while simultaneously directing a plurality of pressurized jetlike streams of quench fluid comprising polyvinyl alcohol and water in said quenching station toward said heated bearing surface portion of said one of said crankshafts; and selecting and maintaining the pressure of said jetlike streams of quench fluid to cause said heated bearing surface portion including the straight cylindrical bearing surface and annular curved fillet surfaces thereof of said one of said crankshafts to be impinged by said jet-like streams at impact velocities ranging from at least three feet per second to substantially nine feet per second.

7. A process for inductively hardening the bearing surface portions of a plurality of crankshafts as set forth in claim 6, wherein said crankshafts are each continually rotated about their longitudinal axis during the aforementioned inductive heating and quenching steps.

References Cited by the Examiner UNITED STATES PATENTS 1,866,538 7/1932 Andrus l48146 X 2,787,566 4/1957 Seulen et al. 148-146 2,930,603 3/1960 Voss et al 148-150 X 2,958,524 11/1960 Delapena et al 266-4 3,174,738 3/1965 Seulen et a1. 148146 X DAVID L. RECK, Primary Examiner. C. N. LOVELL, Assistant Examiner. 

1. A PROCESS FOR INDUCTIVELY HARDENING SURFACE PORTIONS OF A CRANKSHAFT, EACH OF SAID SURFACE PORTIONS INCLUDING A GENERALLY STRAIGHT CYLINDRICAL BEARING SURFACE AND ANNULAR CURVED FILLET SURFACES AT EACH END OF THE BEARING SURFACE, COMPRISING THE STEPS OF, INDUCTIVELY HEATING A SELECTED ONE OF SAID SURFACE PORTIONS; AND IMMEDIATELY THEREAFTER IMMERSING THE ENTIRE CRANKSHIFT BODILY INTO A QUENCH BATH OF POLYVINYL ALCOHOL AND WATER AND SIMULTANEOUSLY CAUSING SAID HEATED SURFACE PORTION TO BE IMPINGED WITH A PLURALITY OF PRESSURIZED, JET-LIKE STREAMS OF POLYVINYL 